JP2012123049A - Exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure device capable of achieving exposure in which light from a light source penetrates an opening of a photomask and a local illuminance distribution of light irradiated on a substrate is almost the same both in a conveyance direction of the substrate and in a direction orthogonal to the conveyance direction for small mask continuous exposure.SOLUTION: An exposure device comprises a light source, a photomask disposed between the light source and a substrate and a fly-eye lens 6 for uniformizing an illuminance distribution of light irradiated on an irradiation region 40 on the photomask. The width of the irradiation region 40 is 1 to 1.5 times the length.

Description

  The present invention relates to an exposure apparatus for exposing a color filter substrate constituting a liquid crystal display device, for example.

  With the recent increase in size of liquid crystal display devices, color filters used in liquid crystal display devices have also increased in size. In the color filter manufacturing process, the colored layer is patterned by a photolithography method. However, since a large exposure mask is very expensive, there is a problem that the manufacturing cost of the color filter increases. Therefore, using an exposure machine in which a photomask smaller than the display pixel area of the color filter substrate is mounted on the exposure head, the entire surface of the substrate to be exposed is repeatedly exposed while the substrate is being transported (hereinafter referred to as “compact”). A mask continuous exposure method). In the small mask continuous exposure method, for example, the opening pattern of the photomask is repeatedly transferred onto the substrate by irradiating light from a blinking light source while transporting the substrate.

  In the small mask continuous exposure, exposure is performed while the substrate is conveyed in one direction. Therefore, it is possible to design the length of the region where the opening pattern is formed in the substrate transport direction (hereinafter referred to as “opening pattern formation region”) short. Therefore, two or more types of opening pattern forming regions having different sizes and pitches can be arranged on the photomask in the transport direction. Thus, exposure is performed by changing the photomask region for each type of color filter, the photomask is used efficiently, and the number of photomasks is reduced.

  In addition, when a flashing light source is used to transfer the opening pattern of the photomask to the substrate being transported in accordance with the flashing of the light, the light is flashed at a high frequency, and the light is flashed at a high energy level. It is necessary to irradiate light. Therefore, laser light may be used as the light source. However, the intensity of the laser light has a Gaussian distribution that increases as it is closer to the center of the optical axis. Therefore, the fly-eye lens is used to make the illuminance distribution of the laser light uniform in the irradiation region. Further, in order to effectively use light from the light source during exposure, the optical system of the exposure apparatus is designed so that the region irradiated with light from the light source is substantially similar to the aperture pattern formation region. .

JP 2006-292955 A

  FIG. 4 is a front view of a fly-eye lens used in a conventional exposure apparatus, and FIG. 5 is a plan view showing an example of a conventional photomask. In the following drawings, the substrate transport direction is the Y axis positive direction.

  The fly-eye lens 106 includes a plurality of single lenses 161 arranged in a matrix. The laser light incident on the fly-eye lens 106 has a concentric intensity distribution in which the intensity of light increases as it approaches the center. Then, the light emitted from each single lens 161 is superimposed on each other and irradiated onto the opening pattern on the photomask 103. An area on the photomask 130 irradiated with light emitted from each single lens 161 is referred to as an irradiation area 140.

  As an example, the photomask 103 shown in FIG. 5 has a length in the X-axis direction (hereinafter referred to as “width”) of 215 mm and a length in the Y-axis direction (hereinafter referred to as “vertical length”) of 60 mm. Designed opening pattern formation regions 132a and 132b are provided. In this manner, by making the vertical length of the opening pattern formation region smaller than the width, two types of opening pattern formation regions 132 a and 132 b are arranged in the Y-axis direction on the photomask 103. Here, as described above, the irradiation region 140 is designed to be substantially similar to the opening pattern formation regions 132a and 132b. Therefore, as shown in FIG. 4, each single lens 161 that emits light to the irradiation region 140 is designed so that the width is three times the vertical length. Therefore, the number of divisions of the single lens with respect to the square fly-eye lens 106 is 4 × 12, and the number of single lenses 161 is different in the X-axis direction and the Y-axis direction. In this case, there are problems as described below.

  FIG. 6 is a graph showing the relationship between the irradiation area and the illuminance distribution. More specifically, the simulation shows what local distribution of the illuminance of light that has passed through the opening pattern of the photomask shows on the substrate. The results are shown. The illuminance distribution indicates the results in the X-axis direction (shown by a solid line) and the Y-axis direction (shown by a broken line). Further, as a simulation condition, the shape of the opening pattern is set to a regular octagon with an interval between opposing sides of 30 μm, the interval between the substrate and the photomask is set to 200 μm, and the light collimation half angle is ± 1.8. Set to degrees. Note that the light emitted from the fly-eye lens 106 has a uniform illuminance distribution in the entire light irradiation region, but the illuminance changes locally.

  Due to the influence of the collimation angle of the irradiation light, the width and the vertical length (about 0.044 mm) of the irradiation region that has passed through the opening pattern are larger than the interval (0.03 mm) between a pair of opposing sides of the opening pattern. It has become. And although the illumination intensity of light is substantially uniform in the center part of an irradiation area | region, in the edge part of both sides, it attenuate | damps respectively outward. Here, the attenuation of the illuminance distribution in the Y-axis direction is smooth, whereas the illuminance distribution in the X-axis direction attenuates stepwise. This is because as the number of single lenses arranged in the X-axis direction decreases, the positional deviation between the irradiation areas of the light emitted from the single lenses adjacent in the X-axis direction increases, and the continuity of illuminance attenuation is lost. caused by.

  When the light transmitted through the opening pattern exhibits a stepwise illuminance distribution as shown in FIG. 6, there is a problem that the shape of the opening pattern of the photomask is not transferred in a similar manner to the resist on the substrate. More specifically, the resist can form an exposure pattern without being dissolved during development when irradiated with light of a predetermined light irradiation amount (resist sensitivity) or more. For example, when the line indicated by the alternate long and short dash line in FIG. 5 is the illuminance at which the resist sensitivity is obtained, the position of the irradiation region where the alternate long and short dash line intersects the illuminance distribution line is the edge of the exposure pattern. Accordingly, the exposure pattern formed after development has a deviation 108a between the width and the vertical length (width> vertical length). On the other hand, when the line indicated by the two-point difference line is illuminance at which resist sensitivity is obtained, a deviation 108b occurs between the width and the vertical length of the exposure pattern (vertical length> width). As described above, due to the difference in the method of attenuation of the illuminance distribution between the X-axis direction and the Y-axis direction, the ratio between the width and the vertical length of the opening pattern of the photomask, and the width and the vertical length of the exposure pattern. The ratio of to and will change.

  Therefore, in the present invention, in the small mask continuous exposure, the exposure in which the illuminance distribution of the light transmitted through the pixel formation pattern on the photomask is substantially the same in the transport direction of the substrate and the direction orthogonal to the transport direction. An object of the present invention is to provide an exposure apparatus that can be realized.

  The present invention relates to an exposure apparatus that repeatedly exposes a substrate while transporting the substrate in a transport direction. The exposure apparatus includes a light source, a photomask disposed between the light source and the substrate, and a fly-eye lens that irradiates the photomask with a uniform illuminance distribution of light emitted from the light source. The fly-eye lens is a lens in which rectangular single lenses are arranged in a matrix in the matrix direction. On the photomask, an irradiation area irradiated with light emitted from the single lens is formed, and the length of the irradiation area in the direction orthogonal to the transport direction is 1 to 1.5 of the length of the irradiation area in the transport direction. Is double.

  According to the present invention, in the small mask continuous exposure, the local illuminance distribution of the light transmitted through the pixel formation pattern of the photomask can be made substantially the same in the substrate transport direction and the direction orthogonal to the transport direction. Thus, the shape of the photomask pixel formation pattern can be transferred to the resist without distortion.

The top view of the exposure apparatus which concerns on embodiment of this invention Side view of the exposure apparatus shown in FIG. Top view of fly-eye lens Plan view of conventional fly-eye lens Plan view showing an example of a conventional photomask A graph showing the relationship between irradiation area and illuminance distribution

(Embodiment)
FIG. 1 is a plan view of the exposure apparatus of the present embodiment, and FIG. 2 is a side view of the exposure apparatus shown in FIG. In the following drawings, the substrate transport direction is the Y-axis positive direction.

  The exposure apparatus 1 according to the present embodiment repeatedly exposes a dot-like colored pattern on a plurality of exposure regions (upwardly hatched portions) on the substrate 7 while conveying the substrate 7. The exposure apparatus 1 includes a transport device 2, a photomask 3, a light source 4, a beam expander 5, and a fly eye lens 6.

  The transport device 2 transports the substrate 7 at a constant speed in the positive Y-axis direction. A black matrix that functions as a light shielding layer is formed in advance on the substrate 7 by a photolithography method or the like. A peripheral dummy pattern and an alignment mark are formed outside the pixel area defined by the black matrix. Further, a resist for forming a colored pattern is applied to the surface of the substrate 7.

  The photomask 3 is disposed between the light source 4 and the substrate 7. Further, as shown in FIG. 1, six photomasks 3 are arranged in two rows in the X-axis direction. Between the photomasks 3 arranged in one row, the photomask 3 arranged in the other column complements. Furthermore, each of the photomasks 3 is formed with a plurality of opening patterns 31 for exposing the colored pattern in an opening pattern forming region 32 (rectangular region indicated by right-up hatching). 1 shows only one opening pattern 31 in the Y-axis direction, the opening pattern 31 may be formed by a plurality of dot-like openings arranged in the Y-axis direction.

  As the light source 4, laser light (for example, YAG laser) blinking at a predetermined interval is used. Note that the intensity of light emitted from the light source 4 follows a Gaussian distribution, and the intensity of light increases as it approaches the center of the optical axis. The light emitted from the light source 4 is enlarged in diameter by the beam expander 5 and enters the fly eye lens 6 (details of the fly eye lens 6 will be described later). The light whose illuminance distribution is made uniform by the fly-eye lens 6 enters the photomask 3. The light incident on the photomask 3 passes through the opening pattern 31 provided in the opening pattern formation region 32 and is irradiated to the exposure region 41 on the substrate 7.

  Next, details of the fly-eye lens 6 will be described with reference to FIG.

  The fly-eye lens 6 is substantially square and includes a plurality of single lenses 61 arranged in an 8 × 12 matrix. The length of the single lens 61 in the X-axis direction (hereinafter referred to as “width”) is 1 to 1.5 times the length in the Y-axis direction (hereinafter referred to as “vertical length”).

  If the fly-eye lens 6 is square, the number of single lenses 61 in the X-axis direction can be increased by making the shape of the single lens 61 close to a square. Thereby, the method of attenuation of the illuminance distribution in the X-axis direction of the light that has passed through the aperture pattern becomes gentler than the simulation result (solid line) in FIG.

  Since the width of the photomask 3 shown in FIG. 1 is determined in advance and the width of the irradiation region 40 needs to be maintained at a constant value, when the width of the single lens 61 is less than one time of the vertical length. The vertical length of the irradiation region 40 becomes large, which is not preferable. In this case, the area of the irradiation region 40 increases, and there is a possibility that the irradiation intensity of light required for exposure cannot be obtained. On the other hand, if the width of the single lens 61 exceeds 1.5 times the vertical length, the number of single lenses in the X-axis direction is reduced, so that the photomask 3 is removed as in the simulation result shown in FIG. The illuminance distribution of the transmitted light is stepped. In this case, since the difference between the illuminance distribution in the X-axis direction and the Y-axis direction becomes large, the position of the outer peripheral edge of the colored layer defined by the edge of the opening pattern is shifted, and the opening pattern of the photomask 3 is distorted and transferred. End up.

  Further, in order to effectively use the light emitted to the irradiation region 40, the opening pattern formation region 32 on the photomask 3 is designed to be substantially similar to the irradiation region 40. As an example, the size of the photomask opening pattern formation region 32 is designed so that the length of the region 41 irradiated on the substrate 7 is 215 mm in the X-axis direction and 150 mm in the Y-axis direction. In this embodiment, instead of providing a plurality of opening pattern formation regions on a photomask, by providing one opening pattern formation region having a large vertical length, local illumination distribution of light transmitted through the opening pattern Can be made uniform.

  Using the exposure apparatus 1 described above, the substrate 7 is conveyed at a constant speed in the Y-axis positive direction, the light source 4 is blinked, and the opening pattern 31 of the photomask 3 is repeatedly transferred in the Y-axis direction. A dot-like colored pattern is formed on the top. As described above, in the exposure apparatus 1, the illuminance distribution in the X-axis direction and the illuminance distribution in the Y-axis direction of light that passes through the opening pattern and is irradiated on the substrate are substantially the same. Therefore, the coloring pattern can be formed so as to be similar to the opening pattern 31.

  In the exposure apparatus according to this embodiment, a dot-shaped coloring pattern is formed using a blinking light source, but the type of light source is not particularly limited. For example, the stripe-shaped coloring pattern may be formed by continuously transferring the stripe-shaped opening pattern of the photomask in the Y-axis direction using an ordinary light source.

  In the exposure apparatus according to this embodiment, the light source, the beam expander, and the fly-eye lens are arranged side by side in a direction perpendicular to the substrate, but these arrangements are not particularly limited. For example, a plurality of mirrors and prisms provided on the optical axis reflect light multiple times at an arbitrary angle, and a beam expander and a fly-eye lens are respectively oriented in an appropriate direction with respect to the optical axis of the reflected light. It may be arranged.

  Further, in the exposure apparatus according to the present embodiment, the light emitted from the fly-eye lens is directly irradiated onto the photomask, but is not particularly limited to including such an optical system. For example, an optical system in which a lens or the like is further provided between the fly-eye lens and the photomask may be used.

  The present invention can be used, for example, in an exposure apparatus for exposing a color filter substrate used in a liquid crystal display device.

DESCRIPTION OF SYMBOLS 1 Exposure apparatus 2 Conveyance apparatus 3 Photomask 31 Opening pattern 32 Opening pattern formation area 4 Light source 40 Irradiation area 41 Exposure area 5 Beam expander 6 Fly eye lens 61 Single lens 7 Substrate

Claims (2)

An exposure apparatus that repeatedly performs exposure on the substrate while transporting the substrate in the transport direction,
A light source;
A photomask disposed between the light source and the substrate;
A fly-eye lens that irradiates the photomask with a uniform illuminance distribution of light emitted from the light source;
The fly-eye lens is a rectangular single lens arranged in a matrix in the matrix direction,
On the photomask, an irradiation area irradiated with light emitted from the single lens is formed, and the length of the irradiation area in the direction orthogonal to the transport direction is the length of the irradiation area in the transport direction. 1 to 1.5 times the exposure apparatus.   2. The exposure apparatus according to claim 1, wherein a ratio of the number of single lenses in the vertical direction of the fly-eye lens to the number of single lenses in the horizontal direction is 1 to 1.5 times.

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